Heat and light colour stability of beverages coloured with a natural carotene emulsion: Effect of synthetic versus natural water soluble antioxidants

Natural carotenoid emulsions are commonly used to colour beverages. However, carotenoids are frequently prone to oxidation, which results in undesirable colour loss. This study investigates the effect of the direct addition to the beverage of water soluble antioxidants on the colour stability in both direct light (sun test) and heat conditions. A synthetic antioxidant, ascorbic acid, is compared to a natural one, a rosemary extract rich in rosmarinic acid. The addition of ascorbic acid results in improved stability to light but has negative effect for heat stability. The addition of rosemary affects both heat and light stability favourably, even though it is not as efficient to prevent carotenoid degradation in the sun test. It can be concluded that the rosemary extract is a good natural alternative to synthetic ascorbic acid. Its combination with ascorbic acid could be very efficient to improve both light and heat stability of beverages coloured with natural carotenoids. (C) 2014 Elsevier Ltd. All rights reserved.